The plastic bag art needs little introduction. Since the advent of inexpensive plastic materials, untold numbers of plastic bags and similar items have been developed and used.
It is simple enough to define the desirable characteristics of a plastic bag. One obviously necessary characteristic is sufficient strength, both in the plastic sheet material itself and in whatever seams may be used to join segments of a bag. It has become extremely popular to create such seams through heat sealing. In this connection, it has become well known that certain plastic materials such as, for example, polyethylene and polypropylene materials, are particularly suitable for forming strong heat seals. Further in this regard, it is also well known to make plastic bag structures having heat sealed seams from laminated sheet materials in which only the mating plies of the sheet materials are of heat sealable material or characteristics (see, for example, U.S. Pat. Nos. 3,456,867; 3,552,638; 4,394,955; and 3,462,070).
Another consideration in the design of a plastic bag is the manner in which it can be decorated with an appealing design or with advertising material, or both. As is well known to those skilled in the art, there are numerous techniques and processes for coating and decorating plastic surfaces. In this regard, it is generally necessary to treat the surfaces of thermoplastic films to render them printable and/or static resistant. Further, it is also known that once plastic surfaces have been so treated or coated in certain manners, it is very difficult--if not impossible--to form a strong heat seal for joining such surfaces. Thus, the nature and manner of the decoration and/or coating are an important consideration in the design of the plastic bags. In particular, it is important to limit the nature of the treatment to areas which are not to be heat sealed during manufacture.
A further consideration in the design of plastic bags is the desire for some form of closing means for the bag opening in order to enclose and protect merchandise in the bag. In this regard, one known closure means comprises a closure flap which may be folded over the bag opening. However, a problem that sometimes arises in connection with closure flaps for plastic bags is the tendency for the closure means to "flap" around loosely, particularly prior to use by a customer, which may hinder the manufacture, the stacking and, eventually, the use of the bags. Thus, in some instances, tape or adhesive have been used to temporarily hold the closure flap in place prior to its use.
A still further desirable characteristic of plastic bags is the provision of a handle to enable the customer or user to conveniently carry his purchase out of the store. Numerous bags have been proposed and used which include a handle member which is normally much stiffer than the remainder of the bag. Handles of this nature are illustrated, for example, in U.S. Pat. Nos. 3,429,498 and 3,693,867. However, such stiff handles add significantly to the cost of manufacturing a bag.
It is also known to make plastic bags with a cutout adjacent the open end which can serve as a handle. However, in such instances, it is necessary to generally provide some type of reinforcement in the handle area, particularly, when the body of the bag is made from very thin sheets of plastic film such as, for example, film of from 1-3 mil thickness. In this regard, it has been proposed to provide double thickness reinforcement in such cutout areas (see, for example, U.S. Pat. No. 3,693,867) or alternatively to extrude the sheet material so as to have a thickened section in the area from which the cutout for the handle opening will be provided. A still further technique which has been employed in the past is to secure a reinforcing patch member to the plastic sheet material in the vicinity of the handle area. Such reinforcing patch members have been secured to the sheet material by means of suitable adhesives and/or by heat sealing techniques.
While many different types of plastic bags and similar items have been developed and used in the prior art, a need still exists for plastic bag structures and methods of manufacture which employ various combinations of desirable features or characteristics, and it is an object of the present invention to provide such a new and improved plastic bag and method of manufacture so as to provide a convenient and useful package and a simplified, efficient and effective method of manufacture.